Where Does Fuel Oil and Home Heating Oil Come From?

Extraction
Generally the first stage in the extraction of crude oil, which is where we get our fuel oil and our home heating oil, is to drill a well into the underground reservoir. The oil collects underground in what are called oil fields, sort of like underground lakes. Historically, in the USA, especially in the southwest oil states, some oil fields existed where the oil rose naturally to the surface, but most were quickly depleted. Often many wells will be drilled into the same reservoir, to ensure that the extraction rate will be economically viable. Also some wells may be used to pump water, steam or various gas mixtures into the reservoir to raise or maintain the reservoir pressure, and so maintain an economic extraction rate.

If the underground pressure in the oil reservoir is sufficient then the oil will be forced to the surface under this pressure. Gaseous fuels or natural gas are usually present, which also supplies needed underground pressure. In this situation it is sufficient to place a complex arrangement of valves on the well head to connect the well to a pipeline network for storage and processing.

Over the lifetime of the well the pressure will fall, and at some point there will be insufficient underground pressure to force the oil to the surface and the remaining oil in the well must be pumped out.

Various techniques aid in recovering oil from depleted or low pressure reservoirs, including Beam Pumps, Electrical Submersible Pumps (ESPs), and Gas Lift. Other techniques include Water Injection and Gas Re-injection, which help to maintain reservoir pressure.